Creating expressway for overlay routing

ABSTRACT

In a method for creating expressway for overlay routing, an existing peer-to-peer network is organized into a plurality of zones. The plurality of zones is organized into a plurality of levels. Neighboring zones are identified for each zone of the plurality of zones. One or more representatives are identified for each neighboring zone. A routing table is created based the plurality of zones, the neighboring zones, the one or more representatives, and the plurality of levels.

CROSS-REFERENCE

[0001] The present invention is related to pending U.S. application Ser. No.______, (Attorney Docket No. 100202082-1) filed on Aug. 29, 2002, and entitled “EXPRESSWAY ROUTING AMONG PEERS”, by Xu et al., which is assigned to the assignee and is incorporated by reference herein in its entirety.

FIELD

[0002] This invention relates generally to network systems. More particularly, the invention relates to expressway routing among peers.

DESCRIPTION OF THE RELATED ART

[0003] Peer-to peer (P2P) systems represent a class of networks that utilize distributed resources and perform critical functions in a decentralized manner. Compared with traditional client/server systems, P2P systems have advantages such as improved scalability and reliability, elimination of hot spots surrounding big servers, better resource utilization, lower cost of ownership, etc.

[0004] Although P2P may indicate a shift in general purpose computing, the early generation of P2P systems were typically limited to information placement and look-up. One drawback and disadvantage of the earlier P2P systems is they could not guarantee information location for requesting applications. For instance, early P2P systems (e.g., Gnutella and Freenet) searched for a requested object, i.e., requested information, by looking for cached copies via flooding (they use heuristics to reduce the number of nodes that have to be flooded). As the result, the search may fail because the cached copies may not exist even when the requested object exists.

[0005] Accordingly, later generations of P2P systems dictated a consistent mapping between an object key to a hosting node. In these systems, an object can always be retrieved as long as the hosting nodes can be reached. The random generation of node identifications and documents keys allow even distribution of the data objects among the hosting nodes. Nodes in these later generation P2P systems comprise an overlay network. Since there is a consistent binding between objects to nodes, locating an object is reduced to the problem of routing to the destination node from the requesting node of where the query is submitted.

[0006] However, these later generation P2P systems also have disadvantages and drawbacks. As an example, the overlay network of the later generation P2P systems had limited capability to take advantage of the heterogeneity (e.g., storage capacity, packet forward capacity, network capacity, etc.) of their underlying network. More particularly, the overlay network of the later generation P2P systems were typically homogeneously constructed over the underlying network. Typically, the overlay network was constructed with network proximity as a guide. As a result, the physical topology of the overlay network may cause uneven node distribution and lead to hotspots (e.g., topology aware Content Addressable Network (CAN) from Berkeley).

SUMMARY

[0007] One embodiment pertains to a method of creating an expressway for overlay routing. The method includes organizing an existing peer-to-peer network into a plurality of zones and organizing the plurality of zones into a plurality of levels. The method also includes identifying neighboring zones for each zone of the plurality of zones and identifying one or more representatives for each neighboring zone. The method further includes creating a routing table based on the plurality of zones, the neighboring zones, the one or more representatives, and the plurality of levels.

[0008] Another embodiment relates to a system for creating an overlay network. The system includes a peer-to-peer network and a routing table associated with each peer of the peer-to-peer network. The routing table of a selected peer comprises includes a plurality of zones, a plurality of neighbor zones for each zone, one or more representative peer for said plurality of neighbor zones, and a plurality of spans. Each zone is configured to encompass a different area of the peer-to-peer network. As a result, a peer is the owner of a base zone and resides in zones that encompass the base zone. Each neighbor zone is associated with a respective zone of the plurality of zones. One or more representative peers are identified for each neighbor zone. Each span is associated with a selected zone and respective neighbor zones.

[0009] Yet another embodiment pertains to a method of creating a routing table for an overlay network in an existing peer-to-peer (P2P) network for a selected peer. The method includes initializing a level indicator and setting a zone variable to an entire space of the existing P2P network. The method also includes comparing the zone variable with a base zone in the existing P2P network of the selected peer and recording zone variable as a zone for a level indicated by the level indicator in response to the zone variable being larger than the base zone.

[0010] Yet another embodiment relates to a computer readable storage medium on which is embedded one or more computer programs. The one or more computer programs implements a method of creating an expressway for overlay routing. The one or more computer programs include a set of instructions for initializing a level indicator and setting a zone variable to an entire space of the existing P2P network. The set of instructions also include comparing the zone variable with a base zone in the existing P2P network of the selected peer and recording zone variable as a zone for a level indicated by the level indicator in response to the zone variable being larger than the base zone.

[0011] Yet another embodiment pertains to an apparatus of creating a routing table for an overlay network in an existing P2P network. The apparatus includes means for organizing an existing peer-to-peer network into a plurality of zones and means for organizing the plurality of zones into a plurality of levels. The apparatus also includes means for identifying neighboring zones for each zone of the plurality of zones and means for identifying one or more representatives for each neighboring zone. The apparatus further includes means for creating a routing table based the plurality of zones, the neighboring zones, one or more representatives, and the plurality of levels.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Various features of the embodiments can be more fully appreciated as the same become better understood with reference to the following detailed description of the embodiments when considered in connection with the accompanying figures, in which:

[0013]FIG. 1 illustrates an exemplary system where an embodiment may be practiced;

[0014]FIG. 2 illustrates an expressway overlay network according to an embodiment;

[0015]FIG. 3 illustrates an exemplary architecture for an expressway routing module shown in FIG. 1 according to another embodiment;

[0016]FIG. 4 illustrates a routing table shown in FIG. 3 in accordance with yet another embodiment;

[0017]FIG. 5 illustrates an exemplary flow diagram according to yet another embodiment;

[0018]FIG. 6 illustrates an exemplary flow diagram according to yet another embodiment; and

[0019]FIG. 7 illustrates a computer system where an embodiment may be practiced.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

[0020] For simplicity and illustrative purposes, the principles of the present invention are described by referring mainly to an exemplary embodiments thereof. However, one of ordinary skill in the art would readily recognize that the same principles are equally applicable to, and can be implemented in, all types of network systems, and that any such variations do not depart from the true spirit and scope of the present invention. Moreover, in the following detailed description, references are made to the accompanying figures, which illustrate specific embodiments. Electrical, mechanical, logical and structural changes may be made to the embodiments without departing from the spirit and scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense and the scope of the present invention is defined by the appended claims and their equivalents.

[0021] In accordance with an embodiment, a peer in a peer-to-peer (P2P) network may be configured to route data utilizing expressway routing. More particularly, an expressway overlay network may be implemented over the existing P2P system. The expressway overlay network may provide a mechanism to find the largest span, i.e., logical distance (e.g., a number of hops), between a source peer and a destination peer. The expressway overlay network may be configured to divide the entire space (e.g., a Cartesian space for a CAN system) of the existing P2P system into zones. The largest zone may encompass the entire space of the existing P2P system. Succeeding layers divide the existing P2P system into smaller zones. Each peer may belong to multiple zones within the respective layers and each zone may have more than one zone representative. However, at the highest layer (e.g., the L^(th) layer), each peer may be a member of a base zone (i.e., the basic or discrete unit of the P2P system). The peer may determine the two largest non-overlapping zones between the peer and the destination. An expressway route is formed between the respective zone representatives of the two zones. Accordingly, a substantially direct route, i.e., an expressway, may be formed in order to route data thereby increasing network throughput and reducing the occurrence of hotspots in the underlying network.

[0022] In another embodiment, a peer may be configured to determine the largest span between the peer and a destination peer by determining the largest zone that does not encompass the destination peer. More particularly, the peer may receive a request to forward data to a destination peer. The peer may be configured to search an expressway routing table. The expressway routing table may associate a zone that the peer belongs therein with a selected level, where each level in the routing table is associated with a differing sized zone for the peer. For each zone at a selected level, the expressway routing table may also include neighboring zones of similar size (or span). The peer may determine the largest zone that does not encompass the destination peer from the search of the expressway routing table. The associated level of the selected largest zone may designate the span between the peer and the destination peer. The peer may further open a communication channel, e.g., a TCP/IP connection, to the zone representative of the destination zone of similar span of the selected largest zone, which includes the destination peer. The largest zone that encompasses the source peer but not the destination peer can always be found, given the way the zones are formed.

[0023]FIG. 1 illustrates an exemplary block diagram of a system 100 where an embodiment may be practiced. It should be readily apparent to those of ordinary skill in the art that the system 100 depicted in FIG. 1 represents a generalized schematic illustration and that other components may be added or existing components may be removed or modified.

[0024] As shown in FIG. 1, the system 100 includes a plurality of peers 110 a . . . 110 n. The peers 110 a . . . 110 n may be configured to exchange information among themselves and with other network nodes over a network 120. The peers 110 a . . . 110 n may be computing platforms (e.g., personal digital assistants, laptop computers, workstations, and other similar devices) that have a network interface. The peers 110 a . . . 110 n may be further configured to execute an application software program that provides the capability to share information (e.g., files, data, applications, etc.) in a peer-to-peer manner. An example of a peer-to-peer software application is KAZAA, NAPSTER, MORPHEUS, or other similar P2P applications.

[0025] The network 120 may be configured to provide a communication channel among the peers 110 a . . . 110 n. The network 120 may be implemented as a local area network, wide area network or combination thereof. The network 120 may implement wired protocols such as Ethernet, token ring, etc., wireless protocols such as Cellular Digital Packet Data, Mobitex, IEEE 801.11b, Wireless Application Protocol, Global System for Mobiles, etc., or combination thereof.

[0026] According to an embodiment, each peer of the peers 110 a . . . 110 b may comprise an expressway routing module 130. The expressway routing module 130 may implement an expressway overlay network for routing data over the existing P2P network, e.g., content addressable network (CAN), CHORD, etc. The expressway overlay network may be configured to divide the entire Cartesian space of the existing P2P system into zones, which is illustrated in FIG. 2.

[0027]FIG. 2 illustrates an expressway overlay network 200 according to an embodiment. It should be readily apparent to those of ordinary skill in the art that the expressway overlay network 200 depicted in FIG. 2 represents a generalized abstraction and that other versions may be implemented.

[0028] As shown in FIG. 2, base zones 205 a . . . 205 n may be the core unit of the underlying P2P network zone. For example, if the existing P2P network is a CAN network, the base zone is a CAN zone. In each base zone 205 a . . . 205 n, a zone representative may be appointed. The zone representative may be considered the owner of the zone and becomes the routing point for data routed to the therein. For example, in zone 205 a, peer 1 is the zone representative.

[0029] In another embodiment, the underlying network may be a Tapestry network. The prefix of the node identification (ID) may be considered a zone that encompasses the respective peer. The smaller the number of bits in the node ID, the larger the zone. Similarly, in yet another embodiment, the underlying network may be a Pastry network. The suffice of the node ID may be considered a zone that encompasses the peer. The smaller the number of bits in the node ID, the larger the zone. The difference between a CAN zone and a Tapestry zone is that the Tapestry zone is no longer Cartesian space. Rather, it is a set of possible node IDs. Note, in a CAN network, the node IDs are pointers and a Cartesian space is a set of pointers.

[0030] As part of the expressway overlay network 200, larger zones may be formed from smaller zones. For example, intermediate zones 210 a . . . 210 b may be formed from the base zones 205 a . . . 205 n. Intermediate zones 215 a . . . 215 n may be formed from intermediate zones 210 a . . . 210 n. The largest zone 220, the entire space of the P2P network, is formed from intermediate zones 215 a . . . 215 n.

[0031] As with the base zone 205 a . . . 205 n, the intermediates zones 210 a . . . 210 n, 215 a . . . 215 n, may elect (or appoint, select, etc.) one or more zone representatives for each zone. For example, peers 1, 3, and 6, individually and in combination, may become a representative for zone 210 a. For example, peer 1 is the zone representative of base zone 205 a as well as members of intermediate zones 210 a and 215 a. As another example, peer 6 may be zone representative for base zone 205 b as well as members of intermediate zones 210 b and 215 b. Similarly, peer 2 can represent zone 205 c and 215 b.

[0032] In accordance with an embodiment, each zone, from base zone to largest zone, may be associated with a level (or span), L. The largest zone 220 may be designated R₀ with the base zone designated as R_(L). Thus, expressway overlay network 200 (see FIG. 2) may have L=3 which is associated with the base zone 205 a . . . 205 n; L=2 associated with intermediate zones 210 a . . . 210 n; L=1 associated with intermediate zones 215 a . . . 215 n; and L=0 for the largest zone 220.

[0033] Returning to FIG. 1, the expressway routing module 130 may also be configured to form expressways between a source peer and a destination to route date according to another embodiment. For example, if peer 1 is to forward data to peer 2, peer 1 may determine that the largest zone that does not encompass the peer 2 is intermediate zone 215 a (see FIG. 2). Subsequently, peer 1 forms a communication channel, e.g., a TCP/IP connection to the zone representative (e.g., peer 2) of intermediate zone 215 b, in FIG. 2, which is peer 2. Accordingly, data is routed in a substantially efficient manner by bypassing as many intermediate peers as possible between peer 1 and peer 2.

[0034] In another embodiment, a source peer may route data by expressways to an intermediate peer. More particularly, a source peer may select the largest neighboring zone based on the closest distance of the neighboring zone to the destination peer. For example, if peer 1 is requested to forward data to peer 7 (shown in FIG. 2), peer 1 may determine that the largest zone that does not encompass peer 7 is again 215 a. Accordingly, peer 1 forms a communication channel to the zone representative, peer 2, of the largest neighboring zone 215 b. Subsequently, peer 2 may search for the largest zone that does not encompass the destination to forward the data. Thus, each intermediate peer searches its routing table to find an expressway route to the destination peer.

[0035]FIG. 3 illustrates an exemplary architecture 300 for the expressway routing module 130 shown in FIG. 1 in accordance with an embodiment. It should be readily apparent to those of ordinary skill in the art that the architecture 300 depicted in FIG. 3 represents a generalized schematic illustration and that other components may be added or existing components may be removed or modified. Moreover, the architecture 300 may be implemented using software components, hardware components, or a combination thereof.

[0036] As shown in FIG. 3, the architecture 300 may include a peer-to-peer module, an operating system 320, the expressway routing module 130, and a network interface. The peer-to-peer module 310 may be configured to provide the capability to a user of a peer to share information with another peer, i.e., each peer may initiate a communication session with another peer. The peer-to-peer module 310 may be a commercial off-the-shelf application program, a customized software application or other similar computer program. Such programs such as KAZAA, NAPSTER, MORPHEUS, or other similar P2P applications may implement the peer-to-peer module 310.

[0037] The expressway routing module 130 may be configured to monitor an interface between the peer-to-peer module 310 and the operating system 320 through an operating system interface 340. The operating system interface 340 may be implemented as an application program interface, a function call or other similar interfacing technique.

[0038] The expressway routing module 130 may include a routing module 350 and a routing table 360. The routing module 350 may be configured to implement the expressway overlay network and the expressway routing. More particularly, the routing module 350 may create an overlay network described with respect to FIG. 2, by implementing routing tables as shown in FIG. 4.

[0039]FIG. 4 illustrates routing table 360 as shown in FIG. 3 in accordance with an embodiment. It should be readily apparent to those of ordinary skill in the art that the routing table 360 depicted in FIG. 4 represents a generalized illustration and that other fields may be added or existing fields may be removed or modified.

[0040] As shown in FIG. 4, the routing table 360 may include a routing level field 405, a zone field 410, and a neighboring zones field 415. In one embodiment, the values in the routing level field 405, the zone field 410, and the neighboring zones 415 are associated or linked together in each entry of the entries 420 a . . . 420 n.

[0041] A value in the routing level field 405 may indicate the span the between zone representatives. The range of values for the level of the zone may range from the basic unit of the P2P system (RL) to the entire space of the P2P system (R₀).

[0042] A value in the zone field 410 may indicate which zones the associated peer is aware thereof. At the R₀ level for peer 1, the zone would be in the entire space of the existing P2P network. For example, with reference to FIG. 2, the entire space of the P2P system is a Cartesian space of two dimensions (x, y). The zone may be indicated by a designation of (0 . . . 1) in the x-direction and (0 . . . 1) in the y-direction. At the R_(L) level for peer 1, the zone may be indicated by a designation of (0 . . . 0.125) in the x-direction and (0.875 . . . 1).

[0043] A values in the neighboring zones field 415 indicate the identified neighbor zones to the peer. A neighbor zone may be determined by whether a zone shares a common border in the coordinate space; i.e., in a d-dimensional coordinate space, two nodes are neighbors if their coordinate spans overlap along d-1 dimensions and abut along one dimension. Continuing on with the above example, at the R₀ level for peer 1, the neighboring zones may be designated as lower neighbor zone: (0 . . . 1)(0 . . . 1) with zone representative as peer 1 and upper neighbor zone (0 . . . 1)(0 . . . 1) with zone representative as peer 1 in the x-direction. The neighboring zones in the y-direction may be designated as lower neighbor zone (0 . . . 1)(0 . . . 1) with zone representative as peer 1 and upper neighbor zone (0 . . . 1)(0 . . . 1) with zone representative as peer 1. Similarly, for peer 1's zone at level L, its lower neighbor along x-direction is the zone (0.875 . . . 1)(0 . . . 875.1) with peer 8 as the representative, whereas it upper neighbor is the zone (0.125 . . . 0.25)(0.875 . . . 1.0) with peer 9 as representative. It should be noted that only representative for neighbor zones at level L need to be kept as hard state (i.e., unmodified), the representatives for neighbor zones at a lower-level are soft states that can be modified on-the-fly to adapt to changing network conditions. In one embodiment, the representatives of a neighbor zone are selected based on closest distance (e.g., number of hops) to the current peer.

[0044] Returning to FIG. 3, the routing module 350 may be implemented as a software program, a utility, a subroutine, or other similar programming entity. In this respect, the routing module 350 may be implemented using software languages such as C, C++, JAVA, etc. Alternatively, the routing module 350 may be implemented as an electronic device utilizing an application specific integrated circuit, discrete components, solid-state components or combination thereof.

[0045] The operating system 320 may be configured to manage the software applications, data and respective hardware components (e.g., displays, disk drives, etc.) of a peer. The operating system 320 may be implemented by the MICROSOFT WINDOWS family of operating systems, UNIX, HEWLETT-PACKARD HP-UX, LINUX, RIM OS, and other similar operating systems.

[0046] The operating system 320 may be further configured to couple with the network interface 330 through a device driver (not shown). The network interface 330 may be configured to provide a communication port for the respective peer over the network 120 (shown in FIG. 1). The network interface 330 may be implemented using a network interface card, a wireless interface card or other similar input/output device.

[0047]FIG. 5 illustrates an exemplary flow diagram for a method 500 creating an overlay network for expressway routing shown in FIGS. 1 and 3 in accordance with another embodiment. It should be readily apparent to those of ordinary skill in the art that this method 500 represents a generalized illustration and that other steps may be added or existing steps may be removed or modified.

[0048] In this embodiment, the overlay network may be constructed for the peers in the underlying P2P network by the respective routing module 350. As shown in FIG. 5, the routing module 350 may initialize a level (or span) indicator, L, to zero (0) and set a zone candidate (or variable), R, to the entire space of the underlying P2P network, in step 505. If the underlying P2P network is a CAN network, R may be set to the entire Cartesian space of the underlying P2P network. Similarly, if the underlying P2P network is a Tapestry network, R may be set to the node ID of the Tapestry network.

[0049] In step 510, the routing module 350 may determine whether the zone candidate, R, is larger than the peer's base zone in the underlying P2P network (e.g., CAN, Tapestry, Pastry, etc.). If the R is determined to be smaller or equal to the base zone of the peer, the routing module may be configured to end.

[0050] Otherwise, if the zone candidate, R, is determined to be larger than the base zone of the underlying P2P network, the routing module 350 may record the zone candidate, R, as the zone for the level indicated by the level indicator, L, in step 515.

[0051] In step 520, the routing module 350 may be configured to identify neighboring zones of similar span at the level, L. In step 525, the routing module 350 may determine zone representative(s) for each neighboring zone. In one embodiment, the zone representative may be selected based on closest distance (e.g., number of hops) to the respective peer. It should be readily apparent to one skilled in the art that other selection criteria (e.g., peer at a minimum distance) could be used to select the zone representatives. In yet another embodiment, the representatives for the neighbor zones are kept in a soft state in the peer to enable maintenance activities to adapt to the changing network conditions.

[0052] In step 530, the routing module 350 may be configured to record the neighboring zones and the respective zone representatives at the level indicated by the level indicator, L. In step 535, the routing module 350 may be configured to increment the level indicator, L, by one. The routing module 350 may also be configured to subdivide the zone candidate, R, into a plurality of zones. For example, in a Cartesian space, the zone candidate, R, may be divided into quarters.

[0053] In step 540, the routing module 350 may select a subzone that encompasses the base zone of the respective peer and set the selected subzone to the zone candidate, R. Subsequently, the routing module 350 may return to the processing of step 510.

[0054]FIG. 6 illustrates an exemplary flow diagram for a method 600 of the expressway routing module 130 and routing module 350 shown in FIGS. 1 and 3 in accordance with another embodiment. It should be readily apparent to those of ordinary skill in the art that this method 600 represents a generalized illustration and that other steps may be added or existing steps may be removed or modified.

[0055] As shown in FIG. 6, the routing module 350 of the expressway routing module 130 may be configured to be in an idle state in step 605. The routing module 350 may monitor the network interface 330 via the operating system 320 (shown in FIG. 3) for any received requests to route data. The requests may be initiated by a user of a peer or the requests may be forwarded to the receiving peer functioning as an intermediate peer.

[0056] In step 610, the routing module 350 may detect a message (or request) received through the network interface 330. The routing module 350 may be configured to temporarily store the message for processing.

[0057] In step 615, the routing module 350 determines whether the message has reached its destination. More particularly, the routing module 350 may check the destination address of the message to determine whether the receiving peer is the destination for the message. If the destination is the receiving peer, the routing module 350 may return to the idle state of step 605.

[0058] Otherwise, in step 620, the routing module 350 may be configured to search the routing table 350 for a largest zone not encompassing the destination. It should be noted that the largest zone that does not encompass the destination can always be found, given the way the zones are determined as described above.

[0059] In step 625, the routing module 350 may be configured to form a communication channel, i.e., an expressway, to the zone representative of the destination zone at the level of the largest zone. The routing module 350 may forward the requested data to the zone representative in the destination zone in step 630. The zone representative will then forward the data to the destination peer. Subsequently, the routing module 350 may return to the idle state of step 605.

[0060]FIG. 7 illustrates an exemplary block diagram of a computer system 700 where an embodiment may be practiced. The functions of the expressway routing module may be implemented in program code and executed by the computer system 700. The expressway routing module may be implemented in computer languages such as PASCAL, C, C++, JAVA, etc.

[0061] As shown in FIG. 7, the computer system 700 includes one or more processors, such as processor 602, that provide an execution platform for embodiments of the expressway routing module. Commands and data from the processor 702 are communicated over a communication bus 704. The computer system 700 also includes a main memory 706, such as a Random Access Memory (RAM), where the software for the expressway routing module may be executed during runtime, and a secondary memory 708. The secondary memory 708 includes, for example, a hard disk drive 710 and/or a removable storage drive 712, representing a floppy diskette drive, a magnetic tape drive, a compact disk drive, etc., where a copy of a computer program embodiment for the expressway routing module may be stored. The removable storage drive 712 reads from and/or writes to a removable storage unit 714 in a well-known manner. A user interfaces with the expressway routing module with a keyboard 716, a mouse 718, and a display 720. The display adaptor 722 interfaces with the communication bus 704 and the display 720 and receives display data from the processor 702 and converts the display data into display commands for the display 720.

[0062] Certain embodiments may be performed as a computer program. The computer program may exist in a variety of forms both active and inactive. For example, the computer program can exist as software program(s) comprised of program instructions in source code, object code, executable code or other formats; firmware program(s); or hardware description language (HDL) files. Any of the above can be embodied on a computer readable medium, which include storage devices and signals, in compressed or uncompressed form. Exemplary computer readable storage devices include conventional computer system RAM (random access memory), ROM (read-only memory), EPROM (erasable, programmable ROM), EEPROM (electrically erasable, programmable ROM), and magnetic or optical disks or tapes. Exemplary computer readable signals, whether modulated using a carrier or not, are signals that a computer system hosting or running the present invention can be configured to access, including signals downloaded through the Internet or other networks. Concrete examples of the foregoing include distribution of executable software program(s) of the computer program on a CD-ROM or via Internet download. In a sense, the Internet itself, as an abstract entity, is a computer readable medium. The same is true of computer networks in general.

[0063] While the invention has been described with reference to the exemplary embodiments thereof, those skilled in the art will be able to make various modifications to the described embodiments without departing from the true spirit and scope. The terms and descriptions used herein are set forth by way of illustration only and are not meant as limitations. In particular, although the method has been described by examples, the steps of the method may be performed in a different order than illustrated or simultaneously. Those skilled in the art will recognize that these and other variations are possible within the spirit and scope as defined in the following claims and their equivalents. 

What is claimed is:
 1. A method of creating expressway for overlay routing, comprising organizing an existing peer-to-peer network into a plurality of zones; organizing said plurality of zones into a plurality of levels; identifying neighboring zones for each zone of said plurality of zones; identifying one or more representatives for each neighboring zone; and creating a routing table based on said plurality of zones, said neighboring zones, said one or more representatives, and said plurality of levels.
 2. The method according to claim 1, wherein said organizing of said existing peer-to-peer network into a plurality of zones further comprises: defining an entire space of said existing peer-to-peer network as a zone at an initial level, said zone being included in said plurality of zones.
 3. The method according to claim 1, wherein said organizing of said existing peer-to-peer network into a plurality of zones further comprises: defining a zone candidate to join said plurality of zones at a selected level; and comparing said zone candidate with a base zone of said existing peer-to-peer network.
 4. The method according to claim 3, further comprising: recording said zone candidate as a zone at said selected level.
 5. The method according to claim 4, further comprising: identifying said respective neighboring zones for said zone candidate in response to said zone being larger than said base zone.
 6. The method according to claim 5, further comprising: selecting one or more representatives for each said respective neighboring zones based on closest distance; and recording said one or more representatives, said respective neighboring zones in said routing table.
 7. The method according to claim 6, further comprising: subdividing said zone into a plurality of subzones; and selecting said subzone based on said subzone encompassing a base zone.
 8. The method according to claim 7, further comprising: setting said subzone as said zone candidate.
 9. A system for creating an overlay network, said system comprising: a peer-to-peer network; and a routing table associated with each peer of said peer-to-peer network, wherein said routing table of a selected peer comprises: a plurality of zones, wherein each zone is of differing size and each zone encompasses a base zone of said selected peer in said peer-to-peer network; a plurality of neighbor zones, each neighbor zone being associated with a respective zone of said plurality of zones; one or more representative peers for each neighbor zone; and a plurality of spans; each span being associated with a selected zone and respective neighbor zones.
 10. The system according to claim 9, further comprising a routing module, wherein said routing module to build said routing table.
 11. The system according to claim 10, wherein said routing module is configured to initialize a span indicator and a zone candidate to an entire space of said peer-to-peer network.
 12. The system according to claim 11, wherein said routing module is configured to compare said zone candidate to a base zone in said peer-to-peer network of said selected peer.
 13. The system according to claim 12, wherein said routing module is configured to cease building said routing table in response to said zone candidate being smaller or equal to said base zone of said selected peer.
 14. The system according to claim 12, wherein said routing module is configured to determine neighbor zones of said zone candidate, said neighbor zones are a subplurality of said plurality of neighbor zones in response to said zone candidate being larger than said base zone of said selected peer.
 15. The system according to claim 14, wherein said routing module is configured to determine one or more representatives for said neighbor zones of similar span and to record said zone candidate as a zone at a span indicated by said span indicator, neighbor zones of said zone candidate, and said one or more zone representative peers for said neighbor zones of said zone candidate.
 16. The system according to claim 15, wherein said routing module is configured to increment said span indicator and subdivide said zone candidate into a plurality of subzones.
 17. The system according to claim 16, wherein said routing module is configured to select a subzone that encompasses said base zone of said selected peer from said plurality of subzones and to set said zone candidate to said subzone.
 18. A method of creating a routing table for an overlay network in an existing peer-to-peer (P2P) network for a selected peer, comprising: initializing a level indicator; setting a zone variable to an entire space of said existing P2P network; comparing said zone variable with a base zone in said existing P2P network of said selected peer; and recording said zone variable as a zone for a level indicated by said level indicator in response to said zone variable being larger than said base zone.
 19. The method according to claim 18, further comprising: identifying neighboring zones to said zone at said level indicated by said level indicator.
 20. The method according to claim 19, further comprising: determining one or more representatives for each neighboring zones.
 21. The method according to claim 20, further comprising: maintaining said one or more representatives in a soft state associated with said selected peer.
 22. The method according to claim 20, further comprising: determining said one or more representatives based on a closest distance to said selected peer.
 23. The method according to claim 22, further comprising: recording neighboring zones and said one or more representatives.
 24. The method according to claim 23, further comprising: incrementing said level indicator; and subdividing said zone into a plurality of subzones.
 25. The method according to claim 24, further comprising: selecting a subzone based on said subzone encompassing said base zone of said selected peer.
 26. A computer readable storage medium on which is embedded one or more computer programs, said one or more computer programs implementing a method of creating an overlay network for expressway routing, said one or more computer programs comprising a set of instructions for: initializing a level indicator; setting a zone variable to an entire space of said existing P2P network; comparing said zone variable with a base zone in said existing P2P network of said selected peer; and recording said zone variable as a zone for a level indicated by said level indicator in response to said zone variable being larger than said base zone.
 27. The computer readable storage medium in according to claim 26, said set of instructions further comprises: identifying neighboring zones to said zone at said level indicated by said level indicator.
 28. The computer readable storage medium in according to claim 27, said set of instructions further comprises: determining one or more representatives for each neighboring zones.
 29. The computer readable storage medium in according to claim 28, said set of instructions further comprises: determining said one or more representatives based on a closest distance to said selected peer.
 30. The computer readable storage medium in according to claim 29, said set of instructions further comprises: recording neighboring zones and said one or more representatives.
 31. The computer readable storage medium in according to claim 30, said set of instructions further comprises: incrementing said level indicator; and subdividing said zone into a plurality of subzones.
 32. The computer readable storage medium in according to claim 31, said set of instructions further comprises: selecting a subzone based on said subzone encompassing said base zone of said selected peer.
 33. An apparatus for creating expressway for overlay routing, comprising means for organizing an existing peer-to-peer network into a plurality of zones; means for organizing said plurality of zones into a plurality of levels; means for identifying neighboring zones for each zone of said plurality of zones; means for identifying one or more representatives for each neighboring zone; and means for creating a routing table based said plurality of zones, said neighboring zones, one or more representatives, and said plurality of levels.
 34. The apparatus according to claim 34, wherein said means for organizing of said existing peer-to-peer network into a plurality of zones further comprises: means for defining an entire space of said existing peer-to-peer network as a zone at an initial level, said zone being included in said plurality of zones.
 35. The apparatus according to claim 33, wherein said means for organizing of said existing peer-to-peer network into a plurality of zones further comprises: means for defining a zone candidate to join said plurality of zones at a selected level; and means for comparing said zone candidate with a base zone of said existing peer-to-peer network.
 36. The apparatus according to claim 35, further comprising: means for recording said zone candidate as a zone at said selected level.
 37. The apparatus according to claim 36, further comprising: means for identifying said respective neighboring zones for said zone candidate in response to said zone being larger than said base zone.
 38. The apparatus according to claim 37, further comprising: means for selecting one or more representatives for each said respective neighboring zones based on closest distance; and means for recording said one or more representatives, said respective neighboring zones in said routing table.
 39. The apparatus according to claim 38, further comprising: means for subdividing said zone into a plurality of subzones; and means for selecting said subzone based on said subzone encompassing said base zone.
 40. The apparatus according to claim 39, further comprising: means for setting said subzone as said zone candidate. 